It is well known to use cams whose position on the cam shaft is adjustable in particular for valve controlled internal combustion engines to provide a controlled variation of the valve timing of the internal combustion engine so that power and exhaust gas emission of the engine can be adapted. In order to adjust at least one cam an outer cam shaft in which a coaxially supported inner cam shaft is arranged is rotated relative to the inner cam shaft. Thus, the cams that are rotatably connected with the outer cam shaft but fixed at the inner cam shaft are moved relative to the cams that are fixed at the outer cam shaft. In order to adjust the cams relative to each other a rotor is used that is supported at a stator and that rotates the inner camshaft relative to the outer camshaft so that a phase shift of the valve timing is facilitated so that the opening times of the valves can be varied.
Double cam shaft systems of this type with an inner cam shaft and an outer cam shaft concentric thereto require improved tolerance compensation compared to systems with a single cam shaft since position variations can occur during operations and/or during assembly of the individual components of the cam phaser and of the cam shafts which are caused in particular by required tolerances that are inherent to the system. These imprecisions can lead to an increased friction and to a blocking of the individual components, in particular between the stator and the rotor.
DE 10 2008 033 230 A1 discloses e.g. a cam phaser for controlling a double cam shaft with a layer configuration with a first rotor shaped output element and a second rotor shaped output element which are arranged parallel to each other with their blade elements, wherein each output element is configured to receive at least one cam shaft of the double cam shaft so that a receiver protrudes laterally from the cam phaser adjustment center, wherein a compensation element is provided to align at least one output element relative to the double cam shaft in order to configure essential components of a valve train for internal combustion engines which include a cam shaft like a gas control valve control shaft with two cams that are adjustable relative to each other and which are in particular directly adjacent to each other. According to DE 10 2008 033 230 A1 the compensation element is a universal joint or a key.
DE 10 2012 105 284 A1 discloses a cam shaft arrangement with an inner cam shaft and an outer cam shaft and with a cam phaser wherein a compensation element is arranged between the inner cam shaft and a rotor of the cam phaser. The compensation element is disc shaped and includes a spherical contact surface for the inner cam shaft which includes a face that is configured accordingly.
DE 10 2015 113 356 A1 discloses an adjustable cam shaft with a cam phaser. The rotor of the cam phaser is centered about a rotation axis by a screw flange wherein a resilient element is arranged between the rotor and the screw flange wherein a torque is transferable through the resilient element while position errors are compensated.